Negative thermal expansion of Ca<sub>2</sub>RuO<sub>4</sub> with oxygen vacancies

Negative thermal expansion of Ca₂RuO₄ with oxygen vacancies

Xu Sen¹, Hu Yangming¹, Liang Yuan^{2, †}, Shi Chenfei³, Su Yuling³, Guo Juan¹, Gao Qilong¹, Chao Mingju¹, Liang Erjun^{1, ‡}

(a)–(c) Temperature dependent changes of (a) orthorhombic strain, (b)–(d) Ru–O(1) bond lengths in (010) and (100) directions, and Ru–O(2) bond length of Ca₂RuO_4.09, Ca₂RuO_3.87, and Ca₂RuO_3.73, (f) RuO₆ octahedra.