# Presentation: 108876

## Structure Investigation of New Oxides Using Synchrotron Radiation

**Hanno zur Loye**
- University of South Carolina
**Tom Vogt**
- Brookhaven National Laboratory - National Synchrotron Light Source

** ****Tom Vogt (left) and Yongjae Lee (right)**

## Beamline X7A

**Diamond-anvil cell and position-sensitive detector **
**during high pressure mode at X7A **

## South Carolina - BNL CollaborationDOE Funding February 2004-February 2007

- H. zur Loye is long time user of X7A
- Collaboration with Tom Vogt grew out of common interests in oxide chemistry
- NSLS X7A offers unique research capabilities for powder samples:
- High resolution powder diffraction experiments
- Including high pressure and variable temperature capabilities
- H. zur Loye spent sabbatical at BNL with Tom Vogt
- Graduate students visit BNL when beamtime is available

## X7A

- Two or three visits per year
- On-site lodging (inexpensive)
- Airfare (variable cost)
- X7A (“free”)
- Beam time is limiting
- Students trained in modern diffraction techniques
- Two manuscripts in preparation
- High pressure studies of Sr3PbNiO6 (submitted)
- Variable temperature study of Ba3NaIr2O9

## New Mixed Valent (+5/+6) Triple Perovskites: Ba3MIr2O9 (M = Li, Na)

- Two new triple perovskites, Ba3LiIr2O9 and Ba3NaIr2O9, were grown from a K/Li or Na hydroxide flux.  The Li and Na atoms are located in the red octahedra, and the iridium atoms are located in the blue octahedra pairs.  Since there is only one crystallographic site for the iridium, the Ir+5 and Ir+6 cations are randomly distributed within the octahedra pairs.

**Ba****3****LiIr****2****O****9**
- Hexagonal P63/mmc
- a = 5.7804(4) Å
- c = 14.302(1) Å
- R1 = 0.0198
- wR2 = 0.0486

**Ba****3****NaIr****2****O****9**
- Hexagonal P63/mmc
- a = 5.866(4) Å
- c = 14.596(1) Å
- R1 = 0.0192
- wR2 = 0.0434

- Kim, S.-J., Smith, M. D., Darriet, J., zur Loye, H.-C., *J. Solid State Chem.*, **2004**, *177*, 1493

## Magnetic Susceptibility of Ba3MIr2O9 (M = Li, Na) (loose single crystals)

- Both Ba3LiIr2O9 and Ba3NaIr2O9 exhibit a magnetic transition at ~ 100K and ~75K, respectively.  Are these changes in the magnetism coupled to a structural transition?

- Ba3LiIr2O9

- Ba3NaIr2O9

## Structure Refinement of Ba3NaIr2O9 Hexagonal P63/mmc to Monoclinic C2/c Transformation on Beamline X7A

- 20K

- 100K

- C2/c

- C2/c

- P63/mmc

- P63/mmc

## Hexagonal vs. MonoclinicTilting of the Polyhedra

- P63/mmc

- C2/c

## High Pressure Studies using Diamond Anvil CellsBNL-NSLSBeam Line X7A

## Slide 11

## End Members of the A3n+3mA’nB3m+nO9m+6n Family

**n [A****3****A’O****6****] Layer**

**m [A****3****O****9****] Layer**

- Stacking *n* [A3A’O6] layers with *m* [A3O9] layers and filling generated B-site

- Stitzer, K. E., Darriet, J., zur Loye, H.-C., “Advances in the Synthesis and Structure Description of 2H-Hexagonal Perovskite Related Oxides”, Curr. Opin. Solid State Mater. Sci., **2001**, *5*, 535-544.

## Single Crystal of Sr3PbNiO6 Grown out of NaCl:First Example of an Inverse K4CdCl6 StructureFirst Example of Trigonal Prismatic Lead(IV)

- Smith, Stalick, zur Loye, Chem. Mater., **1999**, *11*, 2984

## Sr3PbNiO6

**Ni**

**Pb**

**Octahedra**

**Trigonal Prism**

**Sr****3****PbNiO****6**

**Infinite chains of alternating octahedra and trigonal prisms.**
**Nickel is in octahedral**
**coordination while Lead is in a trigonal prismatic coordination environment.**

## Structure Refinement of Sr3PbNiO6as a Function of Pressure

## Sr3PbNiO6:  a- and c-Axes Lengths as a Function of Pressure

## Sr3PbNiO6: Normalized Axes and Unit Cell Volume as a Function of Pressure 

## Bulk Modulus

- The bulk modulus gives the change in volume of a solid substance as the pressure on it is changed

## Equations of StateThe Murnaghan Equation

- One EoS used for fitting isothermal (P-V datasets) is the Murnaghan equation, which can be derived from the assumption that the bulk modulus varies linearly with pressure.
- K = K0 + K’0P, where K’0 is independent of pressure.
- Integration yields the equation below and is good for compressionup to about 10% (V/V0 >0.9)

- Plotting the **Unit Cell Volume vs. Pressure** and fitting to thisequation yields the bulk modulus.

## Sr3PbNiO6:  Change in Unit-Cell Volume as a Function of Pressure

- _Bulk Modulus_
- Sr3PbNiO6
- K = 95.4 GPa
- Data fit to the Murnaghan equation of state.

## Future Work to Look for Structure Transitions

- Variable temperature study of Ba3LiIr2O9
- High Pressure investigation of Ba2LiOsO6 and Ba2LiRuO6
- Samples at BNL - waiting for beam time