Structures of Impurity Defects in Lithium Niobate and Tantalate Derived from Electron Paramagnetic and Electron Nuclear Double Resonance Data
Point intrinsic and extrinsic defects, especially paramagnetic ions of transition metals and rare-earth elements, have essential influence on properties of lithium niobate, LN and tantalate, LT, and often determine their suitability for numerous applications. Discussions about structures of the defe...
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2021-03-01
|
| Series: | Crystals |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4352/11/4/339 |
| _version_ | 1827696538437025792 |
|---|---|
| author | Valentin G. Grachev Galina I. Malovichko |
| author_facet | Valentin G. Grachev Galina I. Malovichko |
| author_sort | Valentin G. Grachev |
| collection | DOAJ |
| description | Point intrinsic and extrinsic defects, especially paramagnetic ions of transition metals and rare-earth elements, have essential influence on properties of lithium niobate, LN and tantalate, LT, and often determine their suitability for numerous applications. Discussions about structures of the defects in LN/LT have lasted for decades. Many experimental methods facilitate progress in determining the structures of impurity centers. This paper gives current bird’s eye view on contributions of Electron Paramagnetic Resonance (EPR), and Electron Nuclear Double Resonance (ENDOR) studies to the determination of impurity defect structures in LN and LT crystals for a broad audience of researchers and students. Symmetry and charge compensation considerations restrict a number of possible structures. Comparison of measured angular dependences of ENDOR frequencies with calculated ones for Li and Nb substitution using dipole–dipole approximation allows unambiguously to determine the exact location of paramagnetic impurities. Models with two lithium vacancies explain angular dependencies of EPR spectra for Me<sup>3+</sup> ions substituting for Li<sup>+</sup> like Cr, Er, Fe, Gd, Nd, and Yb. Self-compensation of excessive charges through equalization of concentrations of Me<sup>3+</sup>(Li<sup>+</sup>) and Me<sup>3+</sup>(Nb<sup>5+</sup>) and appearance of interstitial Li<sup>+</sup> in the structural vacancy near Me<sup>3+</sup>(Nb<sup>5+</sup>) take place in stoichiometric LN/LT due to lack of intrinsic defects. |
| first_indexed | 2024-03-10T12:50:56Z |
| format | Article |
| id | doaj.art-0b4368d3dc06428ea882cffcd52446fa |
| institution | Directory Open Access Journal |
| issn | 2073-4352 |
| language | English |
| last_indexed | 2024-03-10T12:50:56Z |
| publishDate | 2021-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Crystals |
| spelling | doaj.art-0b4368d3dc06428ea882cffcd52446fa2023-11-21T13:04:39ZengMDPI AGCrystals2073-43522021-03-0111433910.3390/cryst11040339Structures of Impurity Defects in Lithium Niobate and Tantalate Derived from Electron Paramagnetic and Electron Nuclear Double Resonance DataValentin G. Grachev0Galina I. Malovichko1Physics Department, Montana State University, Bozeman, MT 59717, USAPhysics Department, Montana State University, Bozeman, MT 59717, USAPoint intrinsic and extrinsic defects, especially paramagnetic ions of transition metals and rare-earth elements, have essential influence on properties of lithium niobate, LN and tantalate, LT, and often determine their suitability for numerous applications. Discussions about structures of the defects in LN/LT have lasted for decades. Many experimental methods facilitate progress in determining the structures of impurity centers. This paper gives current bird’s eye view on contributions of Electron Paramagnetic Resonance (EPR), and Electron Nuclear Double Resonance (ENDOR) studies to the determination of impurity defect structures in LN and LT crystals for a broad audience of researchers and students. Symmetry and charge compensation considerations restrict a number of possible structures. Comparison of measured angular dependences of ENDOR frequencies with calculated ones for Li and Nb substitution using dipole–dipole approximation allows unambiguously to determine the exact location of paramagnetic impurities. Models with two lithium vacancies explain angular dependencies of EPR spectra for Me<sup>3+</sup> ions substituting for Li<sup>+</sup> like Cr, Er, Fe, Gd, Nd, and Yb. Self-compensation of excessive charges through equalization of concentrations of Me<sup>3+</sup>(Li<sup>+</sup>) and Me<sup>3+</sup>(Nb<sup>5+</sup>) and appearance of interstitial Li<sup>+</sup> in the structural vacancy near Me<sup>3+</sup>(Nb<sup>5+</sup>) take place in stoichiometric LN/LT due to lack of intrinsic defects.https://www.mdpi.com/2073-4352/11/4/339impurityintrinsic defectparamagnetic ionlithium niobatelithium tantalateelectron paramagnetic resonance |
| spellingShingle | Valentin G. Grachev Galina I. Malovichko Structures of Impurity Defects in Lithium Niobate and Tantalate Derived from Electron Paramagnetic and Electron Nuclear Double Resonance Data Crystals impurity intrinsic defect paramagnetic ion lithium niobate lithium tantalate electron paramagnetic resonance |
| title | Structures of Impurity Defects in Lithium Niobate and Tantalate Derived from Electron Paramagnetic and Electron Nuclear Double Resonance Data |
| title_full | Structures of Impurity Defects in Lithium Niobate and Tantalate Derived from Electron Paramagnetic and Electron Nuclear Double Resonance Data |
| title_fullStr | Structures of Impurity Defects in Lithium Niobate and Tantalate Derived from Electron Paramagnetic and Electron Nuclear Double Resonance Data |
| title_full_unstemmed | Structures of Impurity Defects in Lithium Niobate and Tantalate Derived from Electron Paramagnetic and Electron Nuclear Double Resonance Data |
| title_short | Structures of Impurity Defects in Lithium Niobate and Tantalate Derived from Electron Paramagnetic and Electron Nuclear Double Resonance Data |
| title_sort | structures of impurity defects in lithium niobate and tantalate derived from electron paramagnetic and electron nuclear double resonance data |
| topic | impurity intrinsic defect paramagnetic ion lithium niobate lithium tantalate electron paramagnetic resonance |
| url | https://www.mdpi.com/2073-4352/11/4/339 |
| work_keys_str_mv | AT valentinggrachev structuresofimpuritydefectsinlithiumniobateandtantalatederivedfromelectronparamagneticandelectronnucleardoubleresonancedata AT galinaimalovichko structuresofimpuritydefectsinlithiumniobateandtantalatederivedfromelectronparamagneticandelectronnucleardoubleresonancedata |