You will be shown an abstract from a materials science research paper. Your task is to extract all synthesis operations described in the abstract into a structured JSON format. Your output should be a JSON array. Each entry in the array should be a JSON object describing a single synthesis operation. This object should have the following fields:

- "trigger": A verbal predicate indicating a synthesis operation. This should be a string extracted directly from the abstract.
- "arguments": An array of arguments specifying aspects of the synthesis operation. Each entry in the array should be a length-2 array formatted as [<argument_text>, <argument_type>]. The `argument_text` should be a string extracted directly from the abstract. The `argument_type` should be one of the following types: ["Recipe_Precursor", "Atmospheric_Material", "Participant_Material", "Recipe_Target", "Solvent_Material"].

For instance, suppose an excerpt from the abstract reads:

Tetraethoxysilane (TEOS, 98%) and cetyltrimethylammonium bromide (CTAB, 98%) were purchased from Fluka. The MTTZ-siloxy derivative (triethoxysilyl-propyl-5-mercapto-1-methyl-tetrazole) was synthesized as previously described [38].

This excerpt includes two operations, which could be annotated as follows.

[{"arguments": [["Tetraethoxysilane", "Recipe_Precursor"], ["cetyltrimethylammonium bromide", "Recipe_Precursor"]], "trigger": "purchased"}, {"arguments": [["MTTZ-siloxy derivative", "Recipe_Target"]], "trigger": "synthesized"}]

In your response, please include the JSON and no other text.

Abstract:
10.1002/aenm.201300174
Low Electron Scattering Potentials in High Performance Mg 2 Si 0.45 Sn 0.55 Based Thermoelectric Solid Solutions with Band Convergence

Mg2(1+x)Si0.45Sn0.537Sb0.013 (x = 0.04, 0.06, 0.08, 0.10, 0.12) compounds were synthesized by a B2O3 flux method.22 Elemental Mg (99%), Si (99.9%), Sn (99.5%) and Sb (99.999%) powders were utilized. All preparation steps were performed in an argon glove box. Raw powders were weighed, and thoroughly mixed in an agate mortar. The starting materials were transferred into an alumina crucible, covered by B2O3 powders and then compacted. The crucibles were placed into a chamber furnace, heated at 973 K for 10 h and finally cooled down to room temperature. The ingots were ground and sieved to ~50 μm and hot pressed in a graphite die of Φ 12.7 mm under a pressure of 80 MPa at 1025 K for 2 h, resulting in compact pellets for property analysis. Sample pellets 12.7 mm in diameter were used to measure the thermal conductivity and Hall carrier concentration, and then cut into rectangular bars for the electrical conductivity and Seebeck coefficient measurements.
[{"arguments": [["B2O3", "Participant_Material"], ["Mg2(1+x)Si0.45Sn0.537Sb0.013", "Recipe_Target"]], "trigger": "synthesized"}, {"arguments": [["Sb", "Recipe_Precursor"], ["Mg", "Recipe_Precursor"], ["Sn", "Recipe_Precursor"], ["Si", "Recipe_Precursor"]], "trigger": "utilized"}, {"arguments": [["argon", "Atmospheric_Material"]], "trigger": "performed"}, {"arguments": [["powders", "Participant_Material"]], "trigger": "weighed"}, {"arguments": [["materials", "Participant_Material"]], "trigger": "transferred"}, {"arguments": [["B2O3", "Participant_Material"]], "trigger": "covered"}, {"arguments": [["pellets", "Participant_Material"]], "trigger": "hot pressed"}]