---
title: "Get AlloyPairDoc documents"
method: GET
path: "/materials/alloys/"
tags: ["Materials Alloys"]
---

# Get AlloyPairDoc documents

`GET /materials/alloys/`

## Query parameters

- `material_ids` string, nullable — Comma-separated list of material_ids to query on
- `formulae` string, nullable — Comma-separated list of end-point formulas to query.
- `_page` integer — Page number to request (takes precedent over _limit and _skip).
- `_per_page` integer — Number of entries to show per page (takes precedent over _limit and _skip). Limited to 1000.
- `_skip` integer — Number of entries to skip in the search.
- `_limit` integer — Max number of entries to return in a single query. Limited to 1000.
- `_fields` string — Fields to project from AlloyPairDoc as a list of comma separated strings. Fields include: `builder_meta` `alloy_pair` `pair_id`
- `_all_fields` boolean — Include all fields.

## Response `200`

Search for a AlloyPairDoc

- ResponseAlloyPairDoc
  - `data` AlloyPairDoc[], nullable — List of returned data
    - `builder_meta` EmmetMeta — Default emmet metadata.
      - `emmet_version` string, nullable — The version of emmet this document was built with.
      - `pymatgen_version` string, nullable — The version of pymatgen this document was built with.
      - `run_id` string, nullable — The run id associated with this data build.
      - `batch_id` string, nullable — Identifier corresponding to the origin of this document's blessed task.
      - `database_version` string, nullable — The database version for the built data.
      - `build_date` string, date-time, nullable — The build date for this document.
      - `license` 'BY-C' | 'BY-NC', nullable — License for the data entry.
    - `alloy_pair` TypedAlloyPairDict, required
      - `@module` string, required
      - `@class` string, required
      - `@version` string, nullable
      - `formula_a` string, nullable
      - `formula_b` string, nullable
      - `structure_a` TypedStructureDict — unresolved $ref
      - `structure_b` TypedStructureDict — unresolved $ref
      - `id_a` unknown
      - `id_b` unknown
      - `chemsys` string, nullable
      - `alloying_element_a` string, nullable
      - `alloying_element_b` string, nullable
      - `alloying_species_a` string, nullable
      - `alloying_species_b` string, nullable
      - `observer_elements` string[], nullable
      - `observer_species` string[], nullable
      - `anions_a` string[], nullable
      - `anions_b` string[], nullable
      - `cations_a` string[], nullable
      - `cations_b` string[], nullable
      - `lattice_parameters_a` number[], nullable
      - `lattice_parameters_b` number[], nullable
      - `volume_cube_root_a` number, nullable
      - `volume_cube_root_b` number, nullable
      - `properties_a` TypedSupportedPropertiesDict
        - `energy_above_hull` number, nullable
        - `formation_energy_per_atom` number, nullable
        - `band_gap` number, nullable
        - `is_gap_direct` boolean, nullable
        - `m_n` number, nullable
        - `m_p` number, nullable
        - `theoretical` boolean, nullable
        - `is_metal` boolean, nullable
      - `properties_b` TypedSupportedPropertiesDict
        - `energy_above_hull` number, nullable
        - `formation_energy_per_atom` number, nullable
        - `band_gap` number, nullable
        - `is_gap_direct` boolean, nullable
        - `m_n` number, nullable
        - `m_p` number, nullable
        - `theoretical` boolean, nullable
        - `is_metal` boolean, nullable
      - `spacegroup_intl_number_a` integer, nullable
      - `spacegroup_intl_number_b` integer, nullable
      - `pair_id` PairID
        - `id_a` unknown, required
        - `id_b` unknown, required
        - `separator` string
      - `pair_formula` string, nullable
      - `alloy_oxidation_state` number, nullable
      - `isoelectronic` boolean, nullable
      - `anonymous_formula` string, nullable
      - `nelements` integer, nullable
      - `members` TypedAlloyMemberDict[], nullable
        - `id_` unknown
        - `db` string, nullable
        - `composition` object, nullable
        - `x` number, nullable
        - `is_ordered` boolean, nullable
    - `pair_id` PairID, required
      - `id_a` unknown, required
      - `id_b` unknown, required
      - `separator` string
  - `errors` Error[], nullable — Any errors on processing this query
    - `code` integer, required — The error code
    - `message` string, required — The description of the error
  - `meta` Meta — Meta information for the MAPI Response.
    - `api_version` string — A string containing the version of the Materials API implementation, e.g. v0.9.5
    - `time_stamp` string, date-time — A string containing the date and time at which the query was executed
    - `total_doc` integer, nullable — The total number of documents available for this query
    - `facet` object, nullable — A dictionary containing the facets available for this query

## Other responses

- `422` — Validation Error

## Changes

> 4 revisions in range; 1 could not be searched.

- **2026-07-31** `54f2f79ab4f8` — 1 info
  - the `api_version` response's property default value changed from `0.87.2.dev13+g62063a867` to `0.87.2.dev19+g3f2daf4f8` for the status `200`
- **2026-07-26** `9aac4fdf4081` — 1 info
  - the `api_version` response's property default value changed from `0.87.2.dev4+g6bd8ed856` to `0.87.2.dev13+g62063a867` for the status `200`

[Change history](https://skmtc.dev/materialsproject/apis/materials-project-api/changes/materials/alloys/get.md)

---

[API](https://skmtc.dev/materialsproject/apis/materials-project-api.md) · [All operations](https://skmtc.dev/materialsproject/apis/materials-project-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/materialsproject/materials-project-api/revisions/70f72d0670df/schema)