Journal of Alloys and Compounds 610 (2014) 600–605

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Journal of Alloys and Compounds

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Vibrational properties of nonlinear optical Bi2ZnOB2O6 single crystalsdoped with Pr3+: l-Raman investigations

http://dx.doi.org/10.1016/j.jallcom.2014.05.0710925-8388/� 2014 Elsevier B.V. All rights reserved.

⇑ Corresponding author. Tel.: +48 61 6653247; fax: +48 61 6653164.E-mail address: Dobroslawa.Kasprowicz@put.poznan.pl (D. Kasprowicz).

D. Kasprowicz a,⇑, T. Runka a, K. Jaroszewski a, A. Majchrowski b, E. Michalski c

a Faculty of Technical Physics, Poznan University of Technology, Nieszawska 13 A, 60-965 Poznan, Polandb Institute of Applied Physics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw, Polandc Institute of Optoelectronics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw, Poland

a r t i c l e i n f o

Article history:Received 27 March 2014Received in revised form 9 May 2014Accepted 12 May 2014Available online 20 May 2014

Keywords:Bi2ZnOB2O6

Rare earth ionsl-Raman spectroscopyBi-functional materials

a b s t r a c t

Nonlinear optical Bi2ZnOB2O6 single crystals doped with Pr3+ ions were grown using the Kyropoulosmethod. The crystals are characterized by the large values of nonlinear optical coefficients as well asthe effective luminescence of exciting Pr3+ ions, which makes them an excellent candidate for NIR toVIS laser converters. In this study the vibrational properties of Bi2ZnOB2O6 single crystals doped withPr3+ ions were investigated for the first time with the use of l-Raman spectroscopy. On the basis ofRaman spectra, the modes symmetry was analyzed and the modes assignment was made to characteris-tic molecular groups BO3, BO4, ZnO4 and BiO6. The Raman scattering data showed that the NLO propertiesof Bi2ZnOB2O6:Pr3+ crystals correspond to the low frequency lattice modes associated with BO3 and BO4

groups as well as Bi3+and Zn2+ ions.� 2014 Elsevier B.V. All rights reserved.

1. Introduction

Recently a number of nonlinear crystals, mostly borates, havedemonstrated laser emission of selected wavelengths in the nearinfrared NIR and/or visible VIS spectral range when doped withrare earth luminescent ions [1–5]. The new wavelengths in suchmaterials can be reached from frequency conversion of a givenlaser emission of active ions with the help of nonlinear optical pro-cesses. The nonlinear response of materials associated with thenonlinear second-order v(2) and third-order v(3) susceptibilitiesgives rise to such processes as second harmonic generation SHG,third harmonic generation THG [6–8], frequency mixing, self-fre-quency doubling SFD or stimulated Raman scattering SRS [9]. Theuse of materials which are activated by means of rare earth ions(crystals, optical glasses and optical polymer fibers) and theirapplication in optoelectronic devices is determined by the rangeof radiation emission [10]. Electron transitions of trivalent rareearth ions, which are of significance for laser applications, takeplace within the 4f shell, leading to the emission of radiation inthe VIS, NIR, and near ultraviolet UV ranges. The new bi-functionalmaterials in which the luminescence laser effect and nonlinearoptical phenomena occur simultaneously are very attractive fornew generation laser devices [11].

Borates are known as very effective nonlinear optical (NLO)materials for frequency conversion of laser emission from NIRtrough VIS and UV, to vacuum-ultraviolet VUV spectral regions[12–14]. The optical properties of borate crystals are related totheir molecular structure. The b-BaB2O4 (BBO), LiB3O5 (LBO), CsB3-

O5 (CBO) or a-BiB3O6 (a-BIBO) crystals are made of three basicstructural units: (B3O6)3�, (B3O7)5�, and (BO3)3� anionic groups.Owing to the planar hexagonal structure of the (B3O6)3� anionicgroup, borate crystals made of this basic unit have greater nonlin-earity compared to the crystals composed of (B3O7)5� and (BO3)3�

anionic groups. These compounds are promising candidates assecond- and third-order optical materials [1]. The nonlinear opticalproperties of these materials led also to the fabrication of numer-ous systems generating red, green, and blue light due to the self-frequency doubling effect [15]. Owing to their structure andchemical properties, some borate crystals are also good matricesfor incorporation of different rare earth (RE) ions allowing elec-tronic transitions in the visible VIS region that would interfere withthe expected NLO properties [16]. The investigated Bi2ZnOB2O6

crystal exhibits chemical stability when doped with selected rareearth ions in order to obtain new generation bi-functional laser fre-quency converters. Owing to its structure, Bi2ZnOB2O6 crystal hasvery attractive linear and nonlinear optical properties [17]. It isan optically positive biaxial optical crystal with relatively largebirefringence (0.085–0.106) [18]. The phase matching range offundamental wavelength predicted from the Sellmeier equations

D. Kasprowicz et al. / Journal of Alloys and Compounds 610 (2014) 600–605 601

is from 981 to 4533 nm. The phase matching directions for type ISHG of 1064 nm determined in ab and bc planes are h = 90�,u = 53� and h = 57�, u = 90�, respectively. Bi2ZnOB2O6 crystals havea wide transmission range from 330 to 3000 nm, with the cutoffedge in ultraviolet range at about 330 nm [19]. The second-orderpolarization components of Bi2ZnOB2O6 crystals, which are givenby the three independent coefficients d31, d32 and d33, have alreadybeen determined at 1064 nm fundamental wavelength [20]. Thecrystals have been shown to have high second and third harmonicgeneration (SHG/THG) efficiency, comparable with those ofwell-known crystals such as BBO or KDP [21]. The polarized Ramanspectra of undoped Bi2ZnOB2O6 crystals have already beenpublished [22]. Our preliminary investigation, which is in progresshas shown that Bi2ZnOB2O6 crystals may be efficiently doped withrare earth ions in order to produce systems which will be able toemit selected wavelengths in the near infrared NIR and visibleVIS spectral range by the emission of excited luminescent ionsand by SHG/THG processes. In this work we present for the firsttime the results of spectroscopic investigations with the use ofl-Raman spectroscopy of new nonlinear borate crystals Bi2ZnOB2O6

doped with trivalent praseodymium Pr3+ ions.

2. Crystal structure

Bi2ZnOB2O6 crystallizes in the orthorhombic structure ofPba2 � C8

2v space group with four formula units in the unit cell. Theunit-cell parameters of Bi2ZnOB2O6 crystal are: a = 10.8200(7) Å,b = 11.0014(7) Å, c = 4.8896(3) Å, Z = 4, V = 582.03(6) Å3 [19]. Thestructure of Bi2ZnOB2O6 is formed by chains of (B3O6)3� and Zn2+

Fig. 1. Drawing of the structure of a Bi2ZnOB2O6 crystal (a) ac plane projection and(b) view along the c axis [26].

ions along the a-axis. Along the c-axis the borate–zinc–oxygen lay-ers alternate with cationic layers made of Bi3+ ions (Fig. 1a and b).

Due to small ionic radius of boron ion, borate crystals have clo-sely packed structures and therefore interstitial doping with rela-tively heavy ions such as RE ions is often impossible. The bestexample of a such structure is crystallization of two BiB3O6 phases,namely monoclinic a-phase and orthorhombic d-phase (like incase of investigated Bi2ZnOB2O6). Although the density of a-phaseis lower than that of d-phase, RE ions cannot be introduced into a-phase [23], while the more dense d-phase (having less ‘‘free space’’)is easily doped with RE ions [24]. This example is good explanationof using stoichiometric amounts of RE ions substituting for Bi3+

ions, that create the only space in the lattice for efficient and defectfree doping. Obviously space distribution of bonding orbitals andtheir correlation with crystallographic structure have here thedominant role. Because of the size similarity of the ionic radii ofPr3+ and Bi3+ ions [25] in Bi2ZnOB2O6 crystals, Bi3+ ions can be effi-ciently substituted by Pr3+ ions. The ionic radii of the substitutedBi3+ and substituting Pr3+ are very close (1.03 and 0.99 Å [25]),what allows us to assume that the inter-ionic distances and latticeconstants do not change significantly upon doping. The Bi2ZnOB2O6

structural unit is presented in Fig. 2.In the Bi2ZnOB2O6 structure, the boron B and oxygen O atoms

occupy the 4c positions, apart from two oxygen atoms (assignedin Fig. 2 as O3 and O7), which occupy the 2a and 2b positions,respectively. Zinc Zn and bismuth Bi atoms are located at 4c posi-tions (C1 symmetry), being four and six-coordinated by the oxygenatoms, respectively [19]. As follows, the oxygen atoms form fourtypes of configurations: three-coordinated BO3 planar groups(D3h symmetry) with B1–O lengths equal to 1.333 (O5), 1.381(O1) and 1.410 (O3) Å; four-coordinated BO4 tetrahedra (Td sym-metry) with four B2–O lengths equal to 1.465 (O7), 1.472 (O6),1.500 (O4) and 1.522 (O8) Å; polyhedra ZnO4 with four verticesaround the Zn atoms with Zn–O lengths equal to 1.933 (O2),1.940 (O5), 1.946 (O4) and 1.952 (O8) Å, and polyhedra BiO6 withsix oxygen atoms around the Bi atoms with Bi1–O lengths equalto 2.168 (O2), 2.217 (O8), 2.297 (O1), 2.442 (O6), 2.548 (O5) and2.669 (O7) Å and Bi2–O lengths equal to 2.133 (O2), 2.153 (O4),2.255 (O6), 2.523 (O1), 2.693 (O8) and 2.779 (O2) Å [26].

3. Crystal growth

Despite its congruent melting near 690 �C and the lack ofunwanted phase transitions, good optical quality Bi2ZnOB2O6 sin-gle crystals, like many other borates, cannot be grown by meansof the Czochralski method. It is caused by a relatively high viscosityof the molten compound deteriorating conditions of mass

Fig. 2. Drawing of the structure unit of Bi2ZnOB2O6 crystal. The Bi, Zn, B and Obelonging to the structural unit under consideration, while the oxygen atomsmarked prime and double prime belong to the neighboring structural unit [26].

Fig. 3. Polarized Raman spectra of Bi2ZnOB2O6:Pr3+ crystal for (a) z(xx)z, z(yy)z andx(zz)x and (b) z(xy)z, y(zx)y and x(yz)x scattering geometry.

Fig. 4. Low-wavelength Raman spectra of Bi2ZnOB2O6:Pr3+ for y(x,x + z)y, x(z,z + y)xand x(y,y + z)x configurations.

602 D. Kasprowicz et al. / Journal of Alloys and Compounds 610 (2014) 600–605

transport on the interface and therefore leading to poor optical andstructural quality of growing crystals. We obtained Bi2ZnOB2O6:Pr3+ single crystals from stoichiometric melts by means of the Kyr-opoulos method, similar to that described in Refs. [17–20]. Thegrowth was carried out in a two-zone resistance furnace from aplatinum crucible under conditions of low temperature gradients.The heating zones were controlled with Eurotherm 906S program-mers. The crucible was placed in the lower zone and in this way wecontrolled the temperature of the melt, while the upper zone wasmainly used to maintain the proper temperature gradient. Thegrowth was carried out on oriented seeds cut in [001] or [100]directions. The melt was slowly cooled at a rate 0.01 K/h and nopulling was used. Bi2ZnOB2O6:Pr3+ crystals grew on a rotating seedin the volume of the melt and were confined within crystallo-graphic faces. The as-grown crystals were withdrawn from themelt and cooled to room temperature at a rate 5 K/h. The ortho-rhombic structure of the obtained single crystals was confirmedby means of powder diffraction measurements. In the [100] orien-tation of the seed the as-grown crystals were elongated along[001] direction due to distinctly higher growth rate in this direc-tion when compared to those in [100] and [010] directions. Wefound that [001] seed orientation was preferable, the as-grownsingle crystals were confined with flat side faces formed mainlyby (100) and (010) crystallographic planes, while the bottom ofthe crystal was the (001) plane. Moreover, the dimensions of thecrystals were similar along three crystallographic axes due to lim-iting of excessive growth along [001] direction by properly chosentemperature gradient in the melt, what made the orientation andcutting of oriented samples for measurements relatively easy.

4. Experimental details

Spectroscopic investigation of Bi2ZnOB2O6:Pr3+ crystals was carried out for ori-ented samples of sizes 5 � 4 � 1 mm with edges parallel to the axes of the referencesystem (xyz). The reference system (xyz) was defined by the following convention:x||a, y||b and z||c, respectively. In the notation used a, b and c denote the crystallo-graphic axes of the orthorhombic system. Orientation of the samples of the crystalsstudied was performed using the Laue method and analytical use of the stereo-graphic Wulff net [27]. The doping concentration of Pr3+ ions in the as-grown crys-tal was close to the concentration 1 at.% of Pr3+ ions in the melt. The Raman studywas performed in back-scattering geometry using a Renishaw InVia Raman spectro-scope equipped with a confocal DM 2500 Leica optical microscope, a thermoelectri-cally (TE)-cooled Ren-Cam CCD detector and Ar+ ion laser working at the 514.5 nmwavelength. The polarized Raman spectra were recorded in single scan with a 60 sexposure time of the CCD detector. The applied power of the laser beam beforefocusing was less than 0.3 mW. The optical spatial resolution for the 50� magnifi-cation objective used for excitation wavelength 514.5 nm was approximately equal1.0 lm. An Edge filter was used to stray Rayleigh light rejection. Complementarymeasurements in the low-wavenumber range (below 100 cm�1) were carried outusing a NExT filter with excitation wavelength 488 nm. In both cases, the instru-mental resolution was better than 2 cm�1. The position of the Raman peaks was cal-ibrated before collecting data using a Si reference sample as an internal standard.The polarized Raman spectra were recorded in the spectral range 100–1500 cm�1,covering the region of internal and external vibrations for scattering geometriesin parallel and crossed polarization.

5. Results and discussion

The primitive unit cell of Bi2ZnOB2O6:Pr3+ crystals has four for-mula units and contains 48 atoms, giving 144 fundamental vibra-tions. The zone-center optic modes predicted from the grouptheory analysis for orthorhombic Bi2ZnOB2O6 crystals (space groupPba2) can be classified according to the following formula:35A1 + 35A2 + 37B1 + 37B2. Three of them (A1 + B1 + B2) are acousticmodes. From the remaining 141 normal modes, all those with A1,A2, B1 and B2 symmetry are Raman-active, while those with A1,B1 and B2 symmetry are IR active [28,29]. The A1 modes weredetected in z(xx)z, z(yy)z and x(zz)x configurations, while A2, B1

and B2 modes in z(xy)z, y(zx)y and x(yz)x configurations, respec-tively. Some of them correspond to the translations of Bi (Pr) and

Zn atoms and BO3 and BO4 groups and remaining modes corre-spond to the stretching, bending and librational vibrations ofBO3, BO4, ZnO4 and BiO6 groups.

The (B3O6)3� ions, which are the basic molecular groups in thestructure, consist of one BO4 tetrahedra and two BO3 planar mole-

D. Kasprowicz et al. / Journal of Alloys and Compounds 610 (2014) 600–605 603

cules. Referring to vibrations of isolated BO4 tetrahedrons of pointgroup symmetry Td, their nine internal vibrations can be classifiedinto four fundamental Raman-active modes: symmetric stretchingvibration m1(A) (�800 cm�1), doubly degenerate bending vibrationm2(E) (450–500 cm�1), triply degenerate anti-symmetric stretchingvibration m3(F2) (980–1200 cm�1) and triply degenerate bendingvibration m4(F2) (500–730 cm�1) [30]. However, characteristic

Table 1Wavenumbers in cm�1 of Raman active modes for Bi2ZnOB2O6:Pr3+ crystals together with

z(xx)z z(yy)z x(zz)x z(xy)z y(zx)y

1415 w 1407 vw1382 w

1345 w 1349 vw 1343 w1331vw

1270 w 1270 w1248 w 1239 w

1122 g 1122 g 1122 g 1122 g1013 vw 1010 w

998 sh/vw 981 vw968 w

960 w918 m 919 vw

873 m 868 m 871 vw

832 vw 833 vw822 vw

803 vw738 m 741 m 739 m 739 w 741 vw

714 w700 s 700 m 700 s 699 w 700 vw

660 vw637 w 637 s 636 w 632 vw 637 vw

603 w 606 vw590 m 590 m581 m 581 m 581 m 579 w 580 w

547 w542 w 538 vw

513 sh/vw508 m 504 w 504 m

495 vw492 w

425 w416 vw

398 s 398 m390 s

359 vw352 vw 353 m 354 vw

347 m320 vw 320 vw 325 vw307 vw

286 w276 w

250 sh/m 250 s231 vs 232 s 234 m/sh

222 s 223 vw211 sh/m 218 w

199 s 200 w

185 m 185 w172 m

161 s 161 vs 166 w155 s 158 w

143 s 143 vs 142 s124 w 124 w

107 wy(x, x + z)y x(z, z + y)x x(y, z + z)x102 101 10288 88 8777 76 7766 66 6638 g 38 g 38 g

vs – Very strong; s – strong; m – medium; w – weak; vw – very weak; g – ghost.

vibrations of isolated BO3 ion with D3h symmetry can be classifiedinto four fundamental modes of which three are Raman-activem01(A01) (�950 cm�1), m03(E0) (1250–1400 cm�1), m04(E0) (�600 cm�1)and infrared active m02(A002) (700–800 cm�1) [31–34]. Moreover,the six-coordinate Bi3+ ions surrounded by six oxygen atoms forma BiO6 configuration, while Zn2+ ions surrounded by four oxygenatoms form a ZnO4 configuration.

the modes assignment.

x(yz)x

1406 vw Stretching vibrations of B–O of BO3 and BO4 groups

1348 sh/w1331 m

1179 vw1122 g1011 w

871 m Stretching vibrations of BO3, BO4 and BiO6 groups849 sh/w

739 vw

700 wBending vibrations of BO3, BO4, BiO6 and ZnO4 groups

611 w

592 w

517 w

488 w428 vw

390 vw Librations and translations of BO3, BO4, BiO6 and ZnO4 groups360 w

310 vw

274 w258 sh/vw

222 w

196 sh/vw190 m

175 m

157 m140 vw

118 m

Translations of BiO6 and ZnO4 groups

604 D. Kasprowicz et al. / Journal of Alloys and Compounds 610 (2014) 600–605

The polarized Raman spectra of Bi2ZnOB2O6:Pr3+ crystalsobtained in the 100–1500 cm�1 spectral range at room tempera-ture for selected z(xx)z, z(yy)z, x(zz)x, z(xy)z, z(zx)y and x(yz)x scat-tering configurations are presented in Fig. 3a and b.

As shown in Fig. 3a and b, the intensities of observed latticemodes are significantly higher than those of modes detected inthe higher wavenumbers range, corresponding to the internalvibrations of Bi2ZnOB2O6:Pr3+. The low-wavenumber Raman spec-tra of Bi2ZnOB2O6:Pr3+ were detected for polarized incident andunpolarized scattered light for the y(x,x + z)y, x(y,y + z)x andx(z,z + y)x configurations (Fig. 4).

The determined wavenumbers of Raman modes are given inTable 1. As follows from Figs. 3 and 4 and Table 1, the modes posi-tioned in the spectral range 1500–700 cm�1 are assigned to thestretching vibrations of B–O bonds in BO3 and BO4 groups andBi–O bonds in BiO6 polyhedra. Only two of all modes recorded inthis spectral range, located at 1270 and around 870 cm�1, areassigned to the Bi–O stretching vibrations [22]. The polarized modepositioned at 918 cm�1 recorded in z(xx)z scattering geometry isassigned to the m01(A01) stretching vibrations of regular planar BO3

groups. The most intensive mode recorded in the spectral range1500–700 cm�1, at 700 cm�1 and the lower intensity mode at738 cm�1 are detected in all the scattering geometries presented,however, their intensities in perpendicular polarizations z(xy)z,y(zx)y and x(yz)x are significantly weaker. An additional modelocated at 714 cm�1 is detected in z(xy)z scattering configuration.These three modes arise from the symmetric stretching m1(A)vibrations of BO4 tetrahedra. The remaining modes occurring inthis range were attributed to triply degenerated m3(F2) and doublydegenerated m03(E0) stretching modes of BO4 and BO3 groups,respectively.

The bending modes of BO3 and BO4 groups and vibrations of Bi–O and Zn–O bonds in BiO6 and ZnO4 polyhedra occur in the spectralrange 660–398 cm�1. The highest intensity mode in this rangerecorded at 637 cm�1 in z(yy)z scattering geometry correspondsto the bending vibration m04(E0) of BO3 regular molecule. The inten-sity of this mode recorded in the other two parallel scattering con-figurations z(xx)z and x(zz)x is significantly lower. The modesdetected in the range 606–611 cm�1 and 416–430 cm�1 areassigned to the vibrations of Bi–O bonds of BiO6 polyhedra andZn–O bonds of ZnO4 tetrahedra, respectively. The double structureband with modes at 581 and 590 cm�1 appearing in the spectrarecorded for the z(xx)z and z(yy)z scattering configurations areassigned to the stretching vibrations of Zn–O bonds of ZnO4 tetra-hedra and Bi–O bonds of BiO6 polyhedra [22]. Moreover, the modecentered at 580 cm�1 is also detected in crossed polarizationsz(xy)z and y(zx)y, while the one near 590 cm�1 is recorded inx(yz)x scattering configuration. Several low intensity modes wereobserved in the spectral range 550–450 cm�1 (the positions ofthe peaks are collected in Table 1) for different scattering configu-rations. These modes arise mainly from the bending vibrationsm2(E) of BO4 tetrahedra and the stretching vibrations of Bi–O bondsof BiO6 polyhedra. A strong band occurring in the Raman spectrumcentered at 398 cm�1 in the z(xx)z scattering geometry and oflower intensity in the z(yy)z geometry can be attributed to Bi–O–Bi vibrations of BiO6 polyhedra [35]. The external/lattice modesassigned to translational and librational motions of BO3 and BO4

groups and Bi and Zn atoms are detected in the spectral rangebelow 390 cm�1. The bands at 143, 161 and 199 cm�1 have thehighest intensity for the z(yy)z scattering configuration. A verystrong mode is observed at 222 cm�1 in the x(zz)x scattering geom-etry. The other lattice modes centered at 231 and 250 cm�1 arerecorded in the z(xx)z and z(yy)z scattering configurations, respec-tively. The Raman modes recorded in the spectral range 140–250 cm�1 mainly correspond to the librational motions of BO3

and BO4 groups, while the translational motions of these molecules

are detected in the higher wavenumber spectral range 330–390 cm�1 with the highest intensity mode at 390 cm�1 recordedin the x(zz)x scattering configuration and a relatively low intensitymode at around 350 cm�1 detected in the z(yy)z geometry. Othervery low intensity modes located in the spectral range 300–330 cm�1 can be assigned to the vibrations of BiO6 units. The lowwavenumber phonons detected using the NExT filter in the spec-tral range below 100 cm�1 are presented in Fig. 4. The lineobserved at 38 cm�1 is an optical ghost of the system, while fourmodes detected above 60 cm�1 and centered at around 67, 78,88, and 103 cm�1 can be assigned to the translational motions ofBiO6 and ZnO4 groups. These low energy vibrations are connectedwith the relatively large atomic masses of Bi and Zn atoms [22,36].The band positions of all analyzed modes of Pr3+doped Bi2ZnOB2O6

crystals correspond to those observed for the undoped Bi2ZnOB2O6

crystals [22]. Since the Raman spectroscopy method is very sensi-tive to structure changes (in some cases the positions of corre-sponding Raman modes change in response to a small changes inthe lattice constants as 10�2–10�3 Å Ref. [37]) the positions of cor-responding the bands in the Raman spectra of pure and Pr3+ dopedBi2ZnOB2O6 crystals were compared. The very low doping withPr3+ ions does not essentially influence the Raman spectra ofBi2ZnOB2O6:Pr3+ crystals in comparison to those of undopedBi2ZnOB2O6 crystals. Moreover, the role of electron–phonon cou-pling in linear and nonlinear optical properties of materials isknown to be important [38]. The vibrational contributions toNLO properties can be estimated from Raman scattering data andcorrespond to the low frequency lattice modes of high intensities[33]. Thus our results indicate that the contributions to NLO prop-erties of Bi2ZnOB2O6:Pr3+ crystals originate from the low frequencyvibrations of BO3 and BO4 groups related to the 390, 250, 231, 199,161 and 143 cm�1 modes. The main contributions of the modesdetected below 100 cm�1 come from translations of Bi3+ and Zn2+

ions. Our Raman scattering data indicate that NLO properties ofBi2ZnOB2O6:Pr3+ crystals are associated with BO3 and BO4 groupsas well as Bi3+ and Zn2+ ions.

6. Conclusions

Nonlinear optical Bi2ZnOB2O6 single crystals doped with Pr3+

ions were grown by means of the Kyropoulos method. Our preli-minary investigation, currently in progress, have shown that Bi2-

ZnOB2O6 may be efficiently doped with rare earth ions. Theproduced systems will be able to emit selected wavelengths inthe near infrared NIR and visible VIS spectral range by the emissionof excited luminescent ions as well as SHG/THG processes. Thestudy by l-Raman method has been performed for Bi2ZnOB2O6:Pr3+ for the first time. From the Raman scattering data we concludethat the NLO properties of Bi2ZnOB2O6:Pr3+ crystals are associatedwith BO3 and BO4 groups as well as the Bi3+or Zn4+ ions. The inves-tigated crystals are very promising new generation laser materialswith laser emission of active rare earth ions as well as very effec-tive NLO energy converters.

Acknowledgement

This work was supported by the Research Project of the PolishMinistry of Sciences and Higher Education DS/64–414/2014.

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