Application of Neutron Powder
Diffraction in Materials Science
NSRRC18, Taiwen Aug. 30, 2012
Qingzhen Huang
NIST Center for Neutron Research, NIST, Gaithersburg, MD 20899
www.ncnr.nist.gov
KxFe2-ySe2
• Chemical composition, x & Y; • Symmetry of crystal structures; • Atoms distribution: Fe vacancy order • Magnetic ordering; • Symmetry of the magnetic structure; • Ordered magnetic moments;
• Relation with superconductivity.
Crystal and magnetic
Structures
Properties
1. Chemical composition 2. Atom and spin arrangements
We want to know: RELATIONSHIPS BETWEEN PROPERTIES AND STRUCTURES
Applications of powder diffraction in superconductivity
Position: 2dsinq = nl, where l is the incident beam wavelength, d and q are the distance between successive hkl planes and Bragg angles of reflections, respectively. Intensity: I = C|Fhkl|
2, where Fhkl is the amplitude of the diffracted X-ray or neutron hkl reflection. X-ray: Fhkl = ∑ fj exp(2pi (hx + ky + lz)) e-2W, where fj is the X-ray atomic scattering factor of atom j for X-ray. Neutron: Fhkl = ∑ bj exp(2pi (hx + ky + lz)) e-2W, where bj is the neutron scattering length for atom j. Magnetic: Fhkl = ∑ qj fMj exp(2pi (hx + ky + lz)) e-2W, where qj and fMj are the magnetic interaction vector and the magnetic form factor for atom j, respectively.
Neutron and X-ray powder diffraction
-1
0
1
2
3
4
5
6
7
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 0.2 0.4 0.6 0.8 1
f (C
)
f (Co
3+)
sin
b(C)=0.6648 cm-12
-Neutron scattering length for Carbon
f(C)-Atomic scattering factor for Carbon
f(Co3+
)-Magnetic form factor for Cobalt
q ?l
Comparison of f(A), b(N), and f(M)
-0.5
0
0.5
1.0
1.5
0 10 20 30 40 50 60 70 80
Ne
utr
on S
catt
erin
g A
mplit
ude
s b
(cm
-12)
Atomic Number Z
H
He
Li
Be
B
C
N
OF
V
Mn
Cr
Fe
Co
Ni
Cu
Zn
Y
D Sr
Ba
Nd
Neutron Scattering Amplitudes
Definition of the vectors relevant in the evaluation of the magnetic structure factor.
e and k are unit vectors in the directions of the scattering and magnetic moment,
respectively. The magnetic interaction vector q is always perpendicular to the
scattering vector.
Information required Recommended
Phase identification & transition
Crystal structure determination & refinement
Light elements detection (H, Be, Li, B, C, N, O, F)
Symmetry analysis due to lattice distortion
Symmetry analysis due to light element shifting
Chemical order-disorder
Composition dependent analysis
Magnetic structure analysis & properties
P, I
P + I
I
P
I
P, I
I, P
P
XRD
XRD+NPD
NPD
XRD
NPD
XRD+NPD
XRD/NPD
NPD
Comparison of XRD and NPD techniques. P: position;
I: intensity of reflections. Intensity and resolution are
high for XRD and low for NPD.
NCNR High Resolution Neutron Powder Diffractometer
BT1
BT1
* Temperature: 0.3 - 1800 K;
* Magnetic Field: 0 - 9 T Vertical;
* More information at www.ncnr.nist.gov
Cu311 1.5401Å
Ge311 2.0784 Å
Ge733 1.1968Å
32 counters
Sample position
* 0 2q 165°
* Pressure: 0 – 1GPa;
Monochromator in-pile Collimation (arcmin)
Monochr. 2Theta
Relative Bragg Intensities
Flux (n s-1cm-2)
Wavelength (Å)
Relative # of reflections
Ge(311)
60'
75o
5.78
1,160,000
2.079
50
Ge(311) 15' 75o 2.86 570,000 2.079 50
Ge(311) 7' 75o 1.44 290,000 2.079 50
Cu(311)
60'
90o
1.84
870,000
1.540
100
Cu(311) 15' 90o 1.00 440,000 1.540 100
Cu(311) 7' 90o 0.54 230,000 1.540 100
Ge(733)
60'
120o
0.31
330,000
1.197
200
Ge(733) 15' 120o 0.20 200,000 1.197 200
Ge(733) 7' 120o 0.11 120,000 1.197 200
Parameters of monochromators
www.ncnr.nist.gov
BT1 Resolution of FWHM (degrees) as a function of 2q (degrees)
www.ncnr.nist.gov
Macromolecules
Zeolites
Minerals and Mining
Inorganic structures
Glass ceramics
Ceramic materials (incl medicals)
Metals and alloys
Cement
Polymers and Fibres
Pharmaceuticals
Forensic science
Materials for energy storage and conversion
Magnetic materials
Catalysis
Peroleum and Petrochemicals
Superconductivity
Composites
Paint and Pigments
Piezo ceramics
Aeronautics and Space Materials
Application of powder diffraction for:
PHYSICS 180 67.164 %
CHEMISTRY 72 26.866 %
MATERIALS SCIENCE 40 14.925 % METALLURGY METALLURGICAL ENGINEERING 15 5.597 %
SCIENCE TECHNOLOGY OTHER TOPICS 8 2.985 % ENGINEERING 5 1.866 %
CRYSTALLOGRAPHY 4 1.493 % ENVIRONMENTAL SCIENCES ECOLOGY 2 0.746 %
INSTRUMENTS INSTRUMENTATION 1 0.373 % MECHANICS 1 0.373 %
NUCLEAR SCIENCE TECHNOLOGY 1 0.373 % SPECTROSCOPY 1 0.373 %
学科 数目 %
2011-7-20
PHYSICAL REVIEW B 3.475 84 27.4510 %
JOURNAL OF SOLID STATE CHEMISTRY 2.34 41 13.3987 %
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NATURE MATERIALS 29.504 5 1.6340 %
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POWDER DIFFRACTION 0.512 5 1.6340 %
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合作发表研究论文的刊物
学术刊物 影响指数 篇数 %
2011-7-20
找到的结果数: ~282
被引频次总计[?] : ~9800
去除自引的被引频次总计: ~9500
施引文献[?] : ~6500
每项平均引用次数[?] : ~34
h-index [?] : ~51
引文报告 2012-7-1 作者=(huang q*) AND 地址=(gaithersburg) 入库时间=所有年份. 数据库=SCI-EXPANDED, CPCI-S.
合作发表研究论文概况
Relationships between carbon constant and property
in MgCxNi3 superconductor
Crystal Structure of Non-oxide
Perovskite Superconductor MgCxNi3. Pm3m, a Å
* Questions:
* C Structure Tc?
* C Tc ? T. He, Q. Huang, A. P. Ramirez, Y. Wang, K. A. Regan, N. Rogado, M. A. Hayward, M. K. Haas, J. S. Slusky, K. Inumaru, H. W. Zandbargen, N. P. Ong, and R. J. Cava. Superconductivity in the non-oxide Perovskite MgCNi3. Nature 411, 6833 (2001).
Carbon Content Affect Tc.
Tc Decreases Linearly with x Decreasing
0.5
0.6
0.8
1.0
1.1
0.84 0.88 0.92 0.96 1.0
U *
10
0
Carbon Content, x
(Å2)
U22
(Ni)
U11
(Ni)
Uiso
(Mg)
Variation of the Temperature Factors
as a Function of Carbon Content x for MgCxNi3
Carbon vacancy affects the position of the Ni atoms;
1000
1100
1200
1300
1400
1500
25 30 35 40 45 50
Co
unts
2 theta (deg)
(100) graphite
MgCxNi3, x
Neutron=0.968 (x
nom=1.05)
Short Range Crystallized Graphite
MgCxNi3, xNeutron=0.968, xNom=1.05
* Perovskite phase stability range
0.88 < x < 1.0 for MgCxNi3;
* Tc decreases systematically with
decreasing x;
* Carbon vacancy affects the position
of the Ni atoms;
What we have concluded:
Reveal the fundamental physics
in Fe-based superconductors
Structural and magnetic phase diagram of
CeFeAsO1-xFx and its relation to
high-temperature superconductivity
JUN ZHAO, Q. HUANG, CLARINA DE LA CRUZ, SHILIANG LI, J. W. LYNN, Y.
CHEN,M. A. GREEN, G. F. CHEN, G. LI, Z. LI, J. L. LUO, N. L. WANG AND
PENGCHENG DAI
NATURE MATERIALS, Vol. 7, 953 (2008)
Fe-based superconductivity
CeFeAsO1-xFx Struct. & Mag. as a Function of Temperature
Magnetic order close to superconductivity in the iron-based layered
LaO1-xFxFeAs systems
de la Cruz, C., Huang, Q., Lynn, JW , Li, JY ., Ratcliff, W .,
Zarestky, JL ., Mook, HA ., Chen, GF ., Luo, JL ., Wang, NL ., Dai, PC
NATURE, 453 (7197): 899-902 (2008)
Charge transform and magnetic order in Fe-based superconductors
RE3+O2-Fe2+As3-
Ba2+Fe2+2As3-
2 (1111)
(122)
CeO1-xFxFeAs
Magnetic controlled physical properties
1. Adjustable Zero Thermal Expansion in Antiperovskite
Manganese Nitride;
2. Magnetocaloric Materials for Commercial Refrigeration.
Adjustable Zero Thermal Expansion in Antiperovskite Manganese Nitride Xiaoyan Song, Zhonghua Sun, Qingzhen Huang, Markus Rettenmayr,
Xuemei Liu, Martin Seyring, Guannan Li, Guanghui Rao, and Fuxing Yin
Negative thermal expansion
Mn3-xCu0.5Ge0.5N Mag. & struct. vs temperature
Adv. Mater. (2011)
* Space telescopes
* Thermo-mechanical actuators
* Precision mechanics and
positioning devices
* Bragg grating wavelength filters
* Microelectronic components
Thermal expansion in materials
Low thermal expansion: |a| ≤ 2.0× 10-6/ K
* Alloy: Fe-Ni-Co
* Compound: Mn3AN(C), FeCo(CN)6
* Micro-crystalline glass: Li2O-Al2O3-SiO2
To approach the ZTE
* PTE+NTE
* Adjusting chemical composition
* Controlling magnetic properties
Applications
Mn vacancies and microstructure of ultrafine nanocrystalline in Mn3xCu0.5Ge0.5N
Data of crystal structure derived from Refined refinements for Mn3xCu0.5Ge0.5N
compounds at 295 K (space group: Pm-3m) and the data for the magnetic phase (M1).
Mean grain size (nm) >1000 ~30 ~12
Refined x 1 0.878 0.787
Symbol Mn1000 Mn878 Mn787
a (Å ) at 295 K 3.90077(6) 3.90021(4) 3.89891 (1)
MMn (mB) at Mn site 2.970(5) 2.71(2) 2.22(3)
Mn vacancies and microstructure of ultrafine nanocrystalline in Mn3xCu0.5Ge0.5N
a, Morphology of nanograins. b, Electron diffraction pattern with indexing. c, High resolution transmission electron microscopy of a local region. The arrows represent the orientations of the nanograins. Combining b and c indicates that the ultrafine nanograins have random orientations as a whole. d, Cubic antiperovskite crystal structure. E, M-model.
Data of crystal structure derived from Refined refinements for Mn3xCu0.5Ge0.5N
compounds at 295 K (space group: Pm-3m) and the data for the magnetic phase (M1).
Mean grain size (nm) >1000 ~30 ~12
Refined x 1 0.878 0.787
Symbol Mn1000 Mn878 Mn787
a (Å ) at 295 K 3.90077(6) 3.90021(4) 3.89891 (1)
MMn (mB) at Mn site 2.970(5) 2.71(2) 2.22(3)
Relationships between magnetic moment and lattice constant
c
d
a) Thermal expansion behavior of three materials having different microstructural length scales. b) Magnetic moments of the three materials as a function of temperature. c) Decreases of Mn magnetic moment under high pressure. d) Changes of the temperature dependence of the lattice parameters under high pressure.
Mechanism for the occurrence of ZTE
NTEM and PTET denote NTE caused by magnetic ordering and PTE caused by temperature, respectively, and aM and aT are the corresponding lattice parameters. ΔaM and ΔaT are the changes in the lattice parameter caused by magnetic ordering and temperature, respectively. In the temperature range between T1 and T2 where ΔaM - ΔaT = 0, the ZTE behavior occurs.
What we have Concluded
1. Long-range AFM ordered MNTE-phase possesses the NTE property;
2. Introduction of Zn vacancies induces and stabilizes the MNTE phase;
3. da(MNTE)/dM is nearly constant;
4. TN of MNTE phase can be tuned by chemical substitution;
5. The Mn-site vacancy dominates the degree and rate of the AFM ordering;
6. ZTE can be achieved by adjust the chemical composion.
Magnetocaloric Materials for Commercial Refrigeration
Nd-Fe-B permanent magnet
Magnetocaloric materials
III: Magnetic field
Magnetocaloric
Mn1-xFexP1-yGey Mag. & struct. vs Magnetic field
Lager MCE, small M-field applied, and small hysteresis.
Magnetocaloric Material Mn1.1Fe0.9P1-xGex
Conclusions:
* First order transition
* Large |DSm|
* 150-450 K T-range
* Low cost and non-toxicity
Questions:
* First order transition?
* Why |DSm| is a function
of Magnetic field?
* Maximum the |DSm| ?
* Lowest field?
Solutions:
* Structure vs T & H
* Structure vs |DSm|
|DSm| up to 35 J/kg K
Between 250 and 306 K
Technique:
* Powder diffraction
* Neutron
Intensity map shows that the (001)-PMP intensity decreases
and the (001)-FMP intensity increases as the magnetic field increases,
or temperature decreases.
Is it the firsr-order transition? Mn1-xFexP1-yGey
For comparison, data normalized from the magnetic entropy change |DSm| are shown.
YM01
Conclusion:
1. |DSm| is linearly proportional
to the FM phase fraction.
2. Maximum |DSm| may be larger
than 100 J/kg K.
Questions:
1. 100%PM FM-phase?
2. Minimum M-field?
6
245.4 K/0 T 253.3 K/2 T
PM-phase FM-phase PM-phase FM-phase
Refined Fraction 56.0(1)% 44.0(1)% 66.7(1)% 33.1(1)%
Refined n(P)/n(Ge) 0.78/0.22 0.87/0.13 0.84/0.16 0.75/0.25
a (Å ) 6.0705(1) 6.1515(1) 6.0698(1) 6.1496(2)
c (Å ) 3.4490(1) 3.3592(1) 3.4522(1) 3.3637(1)
Refined parameters for Mn1.1Fe0.9P0.8Ge0.2
a)
b)
Sample may contain small crystallized size particles
Small crystalline size inhibits the magnetic order!
Mn1-xFexP1-yGey
3g site: Mn
3f site: Fe/Fe
We can conclude that
the system is expected to reach:
1. High magnetic entropy Change;
2. Low magnetic field applied;
3. Small hysteresis.
Thanks!