{
  "alternatives": [
    "piezo-strain-d/cln/cti1999"
  ],
  "meta": {
    "api_version": "v1",
    "attribution": "lithium-niobate.com data compiled by Wentao Jiang; cite the original sources listed per value.",
    "data_version": "0.1.0",
    "documentation": "https://lithium-niobate.com/api/openapi.json",
    "license": {
      "id": "CC-BY-4.0",
      "name": "Creative Commons Attribution 4.0 International",
      "url": "https://creativecommons.org/licenses/by/4.0/"
    },
    "tensor": "piezo-strain-d",
    "variant": "cln"
  },
  "recommended": {
    "default": true,
    "frame": {
      "convention": "unstated",
      "handedness": "right",
      "setting": "crystal-physics",
      "x": "a axis, perpendicular to a mirror plane",
      "y": "in a mirror plane",
      "z": "polar c axis",
      "z_sign_definition": "not stated in this record; tensor form matches this frame by symmetry"
    },
    "full": [
      [
        [
          0.0,
          -20.2979,
          33.19025
        ],
        [
          -20.2979,
          0.0,
          0.0
        ],
        [
          33.19025,
          0.0,
          0.0
        ]
      ],
      [
        [
          -20.2979,
          0.0,
          0.0
        ],
        [
          0.0,
          20.2979,
          33.19025
        ],
        [
          0.0,
          33.19025,
          0.0
        ]
      ],
      [
        [
          -1.03662,
          0.0,
          0.0
        ],
        [
          0.0,
          -1.03662,
          0.0
        ],
        [
          0.0,
          0.0,
          8.68973
        ]
      ]
    ],
    "id": "piezo-strain-d/cln/kushibiki1999",
    "independent": {
      "d15": {
        "value": 66.3805
      },
      "d22": {
        "value": 20.2979
      },
      "d31": {
        "value": -1.03662
      },
      "d33": {
        "value": 8.68973
      }
    },
    "kind": "tensor",
    "name": "Piezoelectric strain constants",
    "notes": "Derived, not a published number. d15 66.4, d22 20.3, d31 -1.04, d33 8.7 pC/N. The hydrostatic d_h = 2 d31 + d33 from this set (about 6.6 pC/N) is within 5% of the measured 6.31 pC/N.",
    "provenance": {
      "derivation": "d = e s^E from the kushibiki1999 e and c^E sets, computed by scripts/build_data.py",
      "source_id": "kushibiki1999",
      "status": "C",
      "transcribed": "2026-10-25"
    },
    "public": true,
    "rank": 3,
    "scale": 1,
    "symbol": "d",
    "symmetry_form": {
      "form": [
        [
          "0",
          "0",
          "0",
          "0",
          "d15",
          "-2*d22"
        ],
        [
          "-d22",
          "d22",
          "0",
          "d15",
          "0",
          "0"
        ],
        [
          "d31",
          "d31",
          "d33",
          "0",
          "0",
          "0"
        ]
      ],
      "mirror": "x = 0 plane (x perpendicular to the mirror, z polar)",
      "point_group": "3m",
      "relations": [
        "d16 = -2 d22",
        "d21 = -d22",
        "d24 = d15",
        "d32 = d31"
      ]
    },
    "tensor": "piezo-strain-d",
    "unit": {
      "display": "pC/N",
      "ucum": "pC/N"
    },
    "variant": "cln",
    "variant_note": "SAW-grade congruent",
    "voigt": [
      [
        0.0,
        0.0,
        0.0,
        0.0,
        66.3805,
        -40.5958
      ],
      [
        -20.2979,
        20.2979,
        0.0,
        66.3805,
        0.0,
        0.0
      ],
      [
        -1.03662,
        -1.03662,
        8.68973,
        0.0,
        0.0,
        0.0
      ]
    ],
    "voigt_convention": {
      "full_from_voigt": "d_ijk = d_iJ x (1 if J<=3 else 1/2) (engineering shear strain)",
      "order": [
        "xx",
        "yy",
        "zz",
        "yz",
        "xz",
        "xy"
      ],
      "shear_strain": "engineering"
    }
  },
  "recommended_note": null,
  "spread": {
    "d15": {
      "max": 69.2,
      "min": 66.3805,
      "n_records": 2
    },
    "d22": {
      "max": 20.8,
      "min": 20.2979,
      "n_records": 2
    },
    "d31": {
      "max": -0.85,
      "min": -1.03662,
      "n_records": 2
    },
    "d33": {
      "max": 8.68973,
      "min": 6.0,
      "n_records": 2
    }
  }
}