Phonons and relaxations in unfilled tetragonal tungsten-bronzes

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378271%3A_____%2F21%3A00553887" target="_blank" >RIV/68378271:_____/21:00553887 - isvavai.cz</a>

Výsledek na webu

<a href="http://perovskitesandotherfws.co-ac.com" target="_blank" >http://perovskitesandotherfws.co-ac.com</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.23647/ca.md20191227" target="_blank" >10.23647/ca.md20191227</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Phonons and relaxations in unfilled tetragonal tungsten-bronzes

Popis výsledku v původním jazyce

The lead-free unfilled tetragonal tungsten-bronzes SBN and CBN had been studied by Raman, infrared and high-frequency dielectric spectroscopies to understand the origin of the phase transition. The substitution in the different channels affects phonon parameters as well as relaxations. Identification of the external modes was done by aid of site group analysis of the structure and respective Raman and IR spectra. It is shown that CBN can show also a small Ca occupancy in the pentagonal channels. Relaxations in SBN show similar qualitative behaviour on increasing Sr content and relaxor behaviour, but for the extreme relaxor samples all frequencies are higher, and the contribution to the permittivity of excitations at GHz-THz range is much stronger. The presence of a soft anharmonic central mode at THz range, and the slowing down of a relaxation at GHz-MHz ranges reveals the coexistence of displacive and order-disorder mechanisms of the phase transition in these materials.

Název v anglickém jazyce

Phonons and relaxations in unfilled tetragonal tungsten-bronzes

Popis výsledku anglicky

The lead-free unfilled tetragonal tungsten-bronzes SBN and CBN had been studied by Raman, infrared and high-frequency dielectric spectroscopies to understand the origin of the phase transition. The substitution in the different channels affects phonon parameters as well as relaxations. Identification of the external modes was done by aid of site group analysis of the structure and respective Raman and IR spectra. It is shown that CBN can show also a small Ca occupancy in the pentagonal channels. Relaxations in SBN show similar qualitative behaviour on increasing Sr content and relaxor behaviour, but for the extreme relaxor samples all frequencies are higher, and the contribution to the permittivity of excitations at GHz-THz range is much stronger. The presence of a soft anharmonic central mode at THz range, and the slowing down of a relaxation at GHz-MHz ranges reveals the coexistence of displacive and order-disorder mechanisms of the phase transition in these materials.

Druh

C - Kapitola v odborné knize

CEP obor

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OECD FORD obor

10302 - Condensed matter physics (including formerly solid state physics, supercond.)

Projekt

<a href="/cs/project/GA16-09142S" target="_blank" >GA16-09142S: Dynamika krystalové mříže a dielektrická odezva v tetragonálních oxidech se strukturou wolframového bronzu</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2021

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název knihy nebo sborníku

Perovskites and other framework structure crystalline materials: new trends and perspectives

ISBN

979-8583096497

Počet stran výsledku

26

Strana od-do

281-306

Počet stran knihy

821

Název nakladatele

Collaborating Academics

Místo vydání

Frontignan

Kód UT WoS kapitoly

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