AUTHOR=Ibragimova Olga , Vaquero Lia , Hussein Zain , Drozd Vadym , Chariton Stella , Prakapenka Vitali , Chuvashova Irina 

TITLE=The synthesis of novel lanthanum hydroxyborate at extreme conditions

JOURNAL=Frontiers in Chemistry

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2023.1259000

DOI=10.3389/fchem.2023.1259000

ISSN=2296-2646

ABSTRACT=<p>The novel structure of lanthanum hydroxyborate La<sub>2</sub>B<sub>2</sub>O<sub>5</sub>(OH)<sub>2</sub> was synthesized by the reaction of partially hydrolyzed lanthanum and boron oxide in a diamond anvil cell under high-pressure/high-temperature (HPHT) conditions of 30 GPa and ∼2,400 K. The single-crystal X-ray structure determination of the lanthanum hydroxyborate revealed: <inline-formula id="inf1"><mml:math id="m1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>P</mml:mi><mml:mover accent="true"><mml:mn>3</mml:mn><mml:mo>¯</mml:mo></mml:mover><mml:mi>c</mml:mi><mml:mn>1</mml:mn></mml:mrow></mml:math></inline-formula>, <italic>a</italic> = 6.555(2) Å, <italic>c</italic> = 17.485(8) Å, Z = 6, R<sub>1</sub> = 0.056. The three-dimensional structure consists of discrete planar BO<sub>3</sub> groups and three crystallographically different La ions: one is surrounded by 9, one by 10, and one by 12 oxygen anions. The band gap was estimated using <italic>ab initio</italic> calculations to be 4.64 eV at ambient pressure and 5.26 eV at 30 GPa. The current work describes the novel HPHT lanthanum hydroxyborate with potential application as a deep-ultraviolet birefringent material.</p>