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We recently reported NaSn<jats:sub>2<\/jats:sub>As<jats:sub>2<\/jats:sub> as a novel vdW-type superconductor with transition temperature (<jats:italic>T<\/jats:italic><jats:sub>c<\/jats:sub>) of 1.3\u2009K. Herein, we present the crystal structure and superconductivity of new material Na<jats:sub>1\u2212<jats:italic>x<\/jats:italic><\/jats:sub>Sn<jats:sub>2<\/jats:sub>P<jats:sub>2<\/jats:sub> with <jats:italic>T<\/jats:italic><jats:sub>c<\/jats:sub>\u2009=\u20092.0\u2009K. Its crystal structure consists of two layers of a buckled honeycomb network of SnP, bound by the vdW forces and separated by Na ions, as similar to that of NaSn<jats:sub>2<\/jats:sub>As<jats:sub>2<\/jats:sub>. Amount of Na deficiency (<jats:italic>x<\/jats:italic>) was estimated to be 0.074(18) using synchrotron X-ray diffraction. Bulk nature of superconductivity was confirmed by the measurements of electrical resistivity, magnetic susceptibility, and specific heat. First-principles calculation using density functional theory shows that Na<jats:sub>1\u2212<jats:italic>x<\/jats:italic><\/jats:sub>Sn<jats:sub>2<\/jats:sub>P<jats:sub>2<\/jats:sub> and NaSn<jats:sub>2<\/jats:sub>As<jats:sub>2<\/jats:sub> have comparable electronic structure, suggesting higher <jats:italic>T<\/jats:italic><jats:sub>c<\/jats:sub> of Na<jats:sub>1\u2212<jats:italic>x<\/jats:italic><\/jats:sub>Sn<jats:sub>2<\/jats:sub>P<jats:sub>2<\/jats:sub> resulted from increased density of states at the Fermi level due to Na deficiency. Because there are various structural analogues with tin-pnictide (SnPn) conducting layers, our results indicate that SnPn-based layered compounds can be categorized into a novel family of vdW-type superconductors, providing a new platform for studies on physics and chemistry of low-dimensional superconductors.<\/jats:p>","DOI":"10.1038\/s41598-018-31295-8","type":"journal-article","created":{"date-parts":[[2018,8,21]],"date-time":"2018-08-21T11:04:45Z","timestamp":1534849485000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":25,"title":["Na1\u2212xSn2P2 as a new member of van der Waals-type layered tin pnictide superconductors"],"prefix":"10.1038","volume":"8","author":[{"given":"Yosuke","family":"Goto","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Akira","family":"Miura","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4508-5779","authenticated-orcid":false,"given":"Chikako","family":"Moriyoshi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yoshihiro","family":"Kuroiwa","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tatsuma D.","family":"Matsuda","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0957-3396","authenticated-orcid":false,"given":"Yuji","family":"Aoki","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yoshikazu","family":"Mizuguchi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2018,8,27]]},"reference":[{"key":"31295_CR1","doi-asserted-by":"publisher","first-page":"189","DOI":"10.1007\/BF01303701","volume":"64","author":"JG Bednorz","year":"1986","unstructured":"Bednorz, J. 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