Crystal Structure, Magnetic Susceptibility, and ESR Measurement of BaCu2(PO4)2

The crystal structure of BaCu 2 (PO 4 ) 2 has been refined from X-ray powder data. BaCu 2 (PO 4 ) 2 crystallizes into a triclinic structure which belongs to the space group P-1, which unit cell constant a = (9.226±0.023)(1) A, b = (9.271±0,018)(1) A, c = (10.516±0,09)(1) A, α = (106.76±0.12)(5) o , β = (101.65±0.16)(5) o , γ = (115.70±0.3)(5) o , V = (717.96±0.05) A 3 , Z = 4, and d cal = 4.20 g.cm -3 . The copper atoms constitute isolated magnetic chains parallel to the [001] direction. The magnetic susceptibility measurement was preformed at temperatures ranging from 4.2 K to 300 K. The magnetic susceptibility shows a broad maximum at around 60 K. The magnetic susceptibility has been interpreted in terms of one-dimensional magnetic system. The temperature dependence of the magnetic susceptibility indicated a good agreement with ladder configuration model. In the ESR measurements, clear electron spin resonance (ESR) was observed. The integrated intensity has a broad maximum at around 60 K, which is consistent with the susceptibility result. A quantitative description gives resonance is the first triplet state of the excitation spectrum of ladder configuration.